limit alarms. (Check model number printed on the unit for option). If ordered with relays, then these relays are programmed during Setup to operate as Normally Open (NO) or Normally Closed (NC). The default setting is Normally Open. Each of these limit relays provides a switched output whenever a limit is reached. The maximum rating for a 120Vac unit is 120Vac @ 0.5 amp or 28 Vdc @ 1.0 amp.
Figure 2. Electro-mechanical Relays Hookup Example
Limit# #4
Limitt# 3#
Instrument
Limit# 2#
Limit# 1#
8
7
6
5
4
3
2
1
Switched | |
SWITCHED OUTPUT | |
|
|
120 VAC @ 0.5 AMPS
120 VAC @ 0.5 AMPS
120 VAC @ 0.5 AMPS
120 VAC @ 0.5 AMPS
Open Collector Option
Whenever a limit is reached (on units with open collector output option) an open collector output provides a return for 5 Vdc signal at 50ma on the output connector, e.g. Limit 1 provides its 5 volt output signal between pins 1 and 2. A solid state control relay with a 5Vdc coil that draws 50 ma. or less is recommended for use as shown in figure 4 below. The monitor supplies +5Vdc on pin #2 and the open collector switch to ground on pin #1. The control relay should be driven by controller’s internal power supply off of pin #2 to avoid introducing ground loops or electrical noise into the unit.
Figure 3. Open Collector Hookup Example
Instrument
2
1
+OUTPUT
LOAD
Solid State Relay, LED, Buzzer etc.
TIMERS
The system features two timers that can be programmed from 1 - 99999 seconds. These timers come in handy when some time- based functions have to be performed. For example, it is possible to start a vacuum pump after a certain amount of preprogrammed time or to shut down a process a certain amount of time after reaching a preprogrammed temperature ,etc. Timers can be programmed to operate in one of three possible modes (see below).
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